Dipper trip mechanism



Feb, 19, 1946; R. A. BECKWITH 59 DIPPER TRIP MECHANISM 2 Sheets-Sheet, 1

Filed Aug. 1, 1944 Feb. 19, 1946. R. A. BECKWITH DIPPER ,TRIP mncmmsmFiled Aug. 1, 1944 2 Sheets-Sheet 2 Patented Feb. 19, 1946 PATENT OFFICEDIPPER TRIP MECHANISM Raymond A. Beckwith,

Milwaukee, Wis., assignor to Koehring Company, Milwaukee, Wis., acorporation I Application August 1, 1944, Serial No. 547,533

3 Claims.

My present invention pertains to theart of excavating machines, andparticularly to the type of these machines knownas power shovels orexcavators, in which a dipper, usually mounted upon a dipper stick,ismounted for excavating work. In machines of this class. the dipper isequipped usually with a drop bottom adapted to be unlatched or unlockedby the operator of the machine in order to discharge the, contents ofthe dipper; a

My invention comprises novel mechanism known in the art as dipper tripmechanism for performing the function of unlatching or dis charging "thecontents of the dipper by opening the bottom thereof in the customarymanner.

My dipper trip mechanism has been designed with a special view ofobtaining reliability of operation and enabling the dipper trip functionto be performed'by very slight physical exertion -incident to fingerpressure upon a controlling operating member conveniently arranged uponone of the main operating levers, in the present instance the crowdlever of the machine. Since the trip latch of the dipper is obviouslyresisting a heavy load or, pressure incident to the dirt'or materialreceived in the dipper, when holding the door against 'the openingmovement thereof, it is very important that a power trip arrangementofthe type of my arrangement be slow but positive in its initial pull onthetrip mechanism, a mode of functioning accomplished by means 'of myimproved mechanism. While the starting movement of tripping the, dipperlatch is" slow, the instrumentalities which I provideafiord anaccelerated 'motion just after the manual initiationof thetrippingoperation is started.

In carrying out my invention, the operation of tripping of the dipper orbucket latch is accomplished entirely by mechanical power in' so far asV the power appliedforjmovingthe latch is concerned, and this of coursedoes not necessitate any physical exertion on the part of the operatorof the excavating machine. V

Various advantages of my mechanical construction of the means fortripping the dipper for opening and discharging actionthereofwill befully apparent upon reference to the following description inconjunction with the accompanyingdrawings, in whichi 7 Figure 1 is aside elevation of the body and boom portions of an excavating dipper orshovel of generally conventional type, the illustration beingsomewhatfragmentary and the general operating instrumentalities for thedipper trip mechanism being shown.-

Figure 2 is a fragmentary side view showing more clearly the arrangementfor mounting of the tripping pawl or dog which works in conjunction withthe toothed wheel and the control lever for said pawl or dog.

Figure 3 is a sectional View bringing out more clearly the arrangementof the parts of the tripping mechanism itself, certain parts beingbroken away, taken on line 33 of Figure 4.

Figure 4 is a side elevation of the members primarily as illustrated inFigure 3.

Figure 5 is a perspective view of the crank lever, dog, and supportingmeans for the latter.

Figure 6 is a view of the dog and itscarrying sleeve and arm support,detached to show the construction clearly.

Describing my improvements in detail, and referring to Figure 1 of thedrawings particularly, I note that the body of the shovel or excavatingmeans is illustrated at A and is a conventional type of body intended tocontain the main operating mechanism of the machine and having aplatform or cab in which the operator stands.

On the body A is carried the customary crowd 25'lever designated 20 andat the upper end of this lever is the depressible or movable fingerpieceI. The member I is connected by a rod 2 and by means of crank levers andsuitable linkage 3 to r a crank lever 4 disposed adjacent the tripmecha- 30 nism unit, for a purpose to be later described. The abovesimple arrangement of parts comprises the. operating devices leadingfrom the lever 20 which is pivoted at 20a to the trip unit carriedsomewhat rearwardly of the machine as located inreference to the leversystem including the lever 20.

Now from the trip unit which is generally designated B in Figure 1, andadjacent'to which the crank lever 4 previously referred to is disposed,there lead certain operating parts which pass to the latch on the dippero'fthe machine, and which latch is tripped in order to open the bottomof the dipper and discharge its contents. Figure 1 illustrates theseoperating parts as including a 45 trip cable II that leads to the dipperalong the boom [5. The boom 15 carries the customary dipper stick anddipper on said stick according to well known arrangement used today. Thecable ll is connected by levers l2 on a suitable 50 axis support |2a toan operating line or cable l3 which in turn is connected to a bell cranklever and linkage system H, the latter directly connected with the tripcrank ill of the trip unit B.

I next pass to anexplanation of the details of 55 the trip mechanismwhich is shown best in Figures 2, 3, and 4 of the drawings. As seen inFigure 3, there is provided a constantly rotating shaft l6, and to theouter end of this shaft 16 is bolted or otherwise secured a toothedwheel or member 1, the attachment bolts of which are designated la.

Supported in the central portion of the wheel I as an inner bearing is anormally non-rotating shaft 9. To provide an outboard bearing for theshaft 9 there is employed a housing or spider member 18. Keyed orotherwise secured to the shaft 9 is sleeve 22 constituting thesupporting part of a pawl supporting crank having two crank arms 8. Thesleeve 22 may be additionally aflixed to the shaft 9 by means of theclamp bolt 23. The arms pivotally carry a pawl or dog 6 mounted upon thesmall axis shaft 29 having bearing in the arms 8 by means of a sleevepart 28 which spans the space between the members 8; En,- circling thissleeve part designated 28 is a coiled or helical spring 21, one end ofwhich is anchored and the other end of which engages pin 29 laterallyprojecting from the pawl or dogfi.

The normal action of the spring 2! will be apparent by reference toFigure 4.

Under normal noneoperating conditions of the trip mechanism a roller 5on the bell crank lever A is so positioned as to be located beneath thepawl 6 in contact therewith, thereby holding the pawl in a slightlyupraised condition in which it is not engaged with the teeth of thetoothed memher 1. i

The trip crank it" previously mentioned is welded, keyed or otherwisesecured to the outer end of the shaft 9 and is operated by said shaft toturn rotatively when the dog or pawl 6 has become engaged with thetoothed member I, whereby to initiate a pull upon the connections thatlead to the dipper latch for the opening or movement of the latter indischarging the dipper.

With the above construction of my general mechanism in mind, the generaloperation of the trip means is as follows:

It will be assumed that the dipper of the excavator has been operated toengage with the earth and become loaded with the materials to beexcavated, the loading operation of course being effected under thecontrol of the crowd lever 29 and other suitable levers of the leverstand in the. body A of the machine. it will be further assumed that thedipper stick has been operated to raise the dipper and the excavatorbody has been swung, we will say, to carry the dipper over a vehicle toreceive the load of material discharged from the dipper or to dischargethe material onto some other place of deposit. 7

When the dipper has been disposed in its discharging position, theoperator, simply by finger touch or movement, depresses the fingerpieceI of the lever 20. This action results in operating the parts 2, 3, and4 whereby to bring the roller 5 of the crank lever- 4 out of engagementwith the underside of the pawl or dog 6. This results in the downward ordropping movement of the pawl under the action of the spring 21, so thepawl, previously not engaged with the teeth of the toothed member 1,will be caused to engage one of these teeth while the member I isrotating under the constant rotative effort of the main shaft It. Theengagement of the pawl 9 with the toothed wheel 1 causes the arm orcrank 8, keyed to the shaft 9, to be picked up, thereby impartingrotation to the shaft 9 along with its secured crank member ID.While-the members 8 and. in are making ne revolution, a sufiicientmovement is imparted to the members [4, l3, l2, and H to 'pull the latchwhich secures closed the bottom of the dipper out of its latchingposition to its released position and thereby effecting dumping ordischarging of the contents of the dipper. While the cranks 8 and H] aremaking one revolution the operator removes his finger from the push pinor fingerpiece I, allowing the bell crank and other connections to thecrank 4 to return to their former position thereby placing the roller 5in the path of the pawl 6 again, so that when the pawl comes in contactwith the roller 5 in the revolution of the toothed member 1 the pawl 6will be automatically disengaged from the teeth 0f the toothed member I,in an obvious manner.

The contact pressure between the pawl 6 and the wheel I at the time ofthe disengagement is very low due to'the vertical position of the cranks8 and i0 and rod l4, attached to the crank ID.

If the operator fails to remove his finger pressure on the member I, itwill be apparent that the pawl 6 will remain in engagement with thetoothed member I, simply re-tripping the dipper trip latch of theexcavator intermittently until the finger pressure on the member I isremoved. The above actiondoes not perform any useful function, and ofcourse the excavator operator will remove his finger pressure as soon ashesees he cannot keep the bottom door closed in relation to the dipperstructure, by maintaining such pressure.

The shaft l6 designed to be either a drum shaft end or the end of aswing shaft, each of which is always found in a shovel dipper of theconstruction to which my invention pertains. However it is within thepurview of my invention that the shaft It} may be any shaft thatoperates at a suitable constant speed such as. that of the swing shaftfor instance. The toothed member Iv is bolted to the fac n end of theshaft It. as previously described, and in the present constructionillustrated said member acts as a ball bearing clamp. The part I'l isaball bearing housing to, which is bolted the supporting or spider memel 8 f r the Outer end of the-sh t 9..

F ur 2. hows the. rol er 5 in the. position assumed thereby to allow thebowl 6 to drop into engagement with the, member 1. A split-bearing cap[9 is employed as a meanslfor supporting a housing I! and member [8 inthe manner above described. a

While the fingerpiGe 0, pin L is, located within the grip of the crowdlever 29. for convenience for thumb operation it is, appare'ntthat, thismember I might be disposed in any suitable position near the operatorfor easy reach by him irrespective of mounting the same u-pona'leversuch as the crowdlever previouslydescribed; 1

When pawl 6 is disengaged-by abutmentv with the roller 5 as previouslydescribed, the upward movement of the pawl causes it. to; strike a stop22a on the crank, arm sleeve- 22,the reby also stopping rotation of thepawl and parts operated thereby, notably the shaft'9, crank Hi andconnected parts.

Having thus described invention; what I claim as new and desire to,secure by Letters Patent of the United States is;

1. In; cl ppe t p mechan sm, a. trip. unit mpr s in comb nat on. a.consta tlyrotatin shaft, an internallytoothed wheelj fixed to. said thewheel engaging portion of the pawl operates 10 within the toothed partof the wheel, and a spring encircling the axis of the pawl normallytending to engage same with the toothed wheel.

3. Mechanism as claimed in claim 1, in which the wheel engaging portionof the pawl operates within the toothed part of the wheel, and a springencircling the axis of the pawl normally tending to engage same with thetoothed wheel, the

toothed wheel being coaxial'with and attached to an end of theconstantly rotating shaft, a fixed bearing for said constantly rotatingshaft, and a' spider carried by said bearing and extending outwardlytherefrom and provided with an outboard bearing spaced from the wheeland receiv- 7 ing the outer end of the normally stationary shaft.

RAYMOND A. BECKWITH.

